Co-transformation

hello, i already done the transformation of my insert into new vector in dh5a host and extracted into a plasmid (CYP3A4-pcWori-dh5a plasmid). then my lecturer said that i need to perform a co-transformation in oxy-reductase vector (pCYAC-OXR) before express the protein, so can i just do the co-transformation of CYP3A4-pcWori-dh5a (Amp resistant) and pCYAC-OXR ( chloramphenicol resistant) plasmid like doing standard transformation? or there have different methods.
now, i just do the standard transformation by put in 25ng of CYP3A4-pcWori-dh5a+ 25ng pCYAC-OXR into dh5a competent cell and streak on chloramphenicol 100ug/ul plate..the result is negative.

thank you for your opinion, the purpose of co-transformation is to insert another plasmid into a host which is will help my vector-insert to be expressed well. Right now, i already got it by performing standard transformation with combination of two plasmid in less than 10% of competent cell volume..thank you very much